Whether you have, or don't have to follow a specific tactic in PvP, is arguable. If you want to aim for the best outcome, then it's likely you will have to follow one in a set of certain tactics. That set, isn't much bigger than PvE's set, either. Look at your 11 "potential strategies", for example, a lot of them (i.e: #8, 9, 10, 11) aren't really a strategy, more like some tricks / parts in a strategy - which there are similar parts in PvE strategy too. You may have not noticed since you did only LFR, which require little to no tactic, but judging PvE based on that will be similar to someone AFK in BG or only do some random BG and judge PvP to be boring and zerg-ish.
As for lowering performance, even in PvP, you can mess around with various stuff, but more often than not, you won't get the best result - which is the same in PvE. In arena, for example, while people usually claimed "it's real people and not AI", to me it didn't seem that much different back then. 9 out of 10 games, I could pretty much tell which strategy a team is going to use, who in my team / their team will likely be targeted first, when it will be dangerous, etc. It was far from unpredictable. If we lost, it was more because we didn't have the strat / skill to counter theirs, and not because we didn't see what was coming. Same for RBG, even before the game starts, we had a clear idea of what to do (i.e: X and Y go to zone A, if success, do (1), if not, do (2)) So saying there aren't optimal strats in PvP isn't entirely correct. "For creative, you don't have to" is true. But generally, if you do something just "for creative" in PvP, it's likely you will likely contribute little to victory.